Question

State the principle of a step-up transformer. Explain, with the help of a labeled diagram, its working ?

Answer 1

 Transformer:

Principle: It is a device which converts high voltage AC into low voltage AC and vice-versa. It is based upon the principle of mutual induction. When alternating current is passed through a coil, an induced emf is set up in the neighbouring coil.

Working: When an alternating current is passed through the primary, the magnetic flux through the iron core changes, which does two things. It produces emf in the primary and an induced emf is also set up in the secondary. If we assume that the resistance of primary is negligible, then the back emf will be equal to the voltage applied to the primary.

`therefore V_1 = -N_1 (dphi)/(dt)`

and`,V_2 = -N_2 (dphi)/dt`

Where, N₁ and N₂ are number of turns in the primary and the secondary respectively and V₁ and V₂ are their voltages respectively

In a step-up transformer: N₂ > N₁, therefore, V₂ > V₁